NEC Course Unit Question Help

[GingerZap]

I am in an Electrical Program taking an NEC 1 class and my teacher is no help. I am wanting to check my work to make sure I am on the right track. Below is the question and how I solved it. Can anyone verify if my answer is correct?

What is the minimum neutral demand load (in kW) for 12 apartments, each containing an 8-kW range?
21.5kW

(12 Ranges x 8-kW = 96kW Load) Derate load by multiplying demand factor percentage (32%) as per Table 220.55 Column B. (96kW x .32 = 30.72kW) Derate load by multiplying demand factor 70% for neutral demand load as per 220.61(B) (30.72kW x .7 = 21.5kW)

 

[david luchini]

I am in an Electrical Program taking an NEC 1 class and my teacher is no help. I am wanting to check my work to make sure I am on the right track. Below is the question and how I solved it. Can anyone verify if my answer is correct?

What is the minimum neutral demand load (in kW) for 12 apartments, each containing an 8-kW range?
21.5kW

(12 Ranges x 8-kW = 96kW Load) Derate load by multiplying demand factor percentage (32%) as per Table 220.55 Column B. (96kW x .32 = 30.72kW) Derate load by multiplying demand factor 70% for neutral demand load as per 220.61(B) (30.72kW x .7 = 21.5kW)

The demand for 12 ranges is 27kW (Col C)

 

[augie47]

Note that Note 3 to Table 220..55 says "it shall be permissible" to use Col B.
As David points out, in this case, Col C gives you a smaller number.

 

[GingerZap]

Thank You David and Augie.